1. Field of the Invention
The present invention relates to a data communications system, and in particular to a system using an extensive public network such as the Internet.
2. Related Art
Hitherto, users have typically been charged for Internet usage following a subscription model in which they pay a flat-rate fee to an Internet Services Provider (ISP) for access to the Internet and use of network resources is subsequently free of charge. The different networks and routers making up the Internet have then endeavoured to meet the need of any particular application on a “best effort” basis. It has been recognised that this method of operation is not appropriate for applications such as multimedia conferencing which use a lot of network resources, and which ideally require a guaranteed quality of service (QoS). A customer for such services may therefore pay a premium to an Internet service provider in order to receive a guaranteed QoS for a given session, or over an extended period of time. More generally, there may be a need to charge customers according to the amount of data transmitted. This might be used, for example, to provide a charging mechanism for access to on-line data sources, such as a video library.
Where the customer is paying for a certain specified quality of service, or for a certain amount of data received, there arises the problem of resolving any disputes between the customer and the service provider as to the level of service the customer has received in a given period. A customer might, for example, pay for an enhanced QoS level for a session of video conferencing. If however the network or service provider then fails to provide the required QoS, for example because a high proportion of data packets has been lost or because the video source became over-loaded, then the customer might claim a refund. However, while conventional networks, such as the PSTN, incorporate extensive and reliable billing systems which carefully record details of all calls and generate reliable records, no such billing/auditing structure exists within or across the Internet. Moreover, it would be undesirable to incorporate a conventional billing structure in the Internet or any other similar public data network, since this would add considerably to the operational costs of the network. There remains a need therefore for alternative mechanisms for resolving any disputes between parties as to the quality of service which has been delivered.